The anterior and posterior cruciate ligaments of the human knee cooperate with other ligaments and soft tissue to provide static and dynamic stability to the joint. Often, the anterior cruciate ligament (ACL) is ruptured or torn as a result of, for example, sports related activities. Consequently, various surgical procedures have been developed for reconstructing the ACL and restoring normal function to the knee.
In many instances, the ruptured ACL is replaced by substituting a harvested or synthetic graft ligament. More particularly, a graft ligament is extended across the interior of the joint and its two opposing ends are anchored to the femur and tibia bones, respectively. Typically, the graft ends are anchored by first forming bone tunnels in the femur and tibia, then extending the graft ends either part way or all the way through the bone tunnels in the femur and tibia, and then making the graft ends fast, either to the side walls of the bone tunnels or to the exterior surfaces of the bones. The graft is anchored in place by means well known in the art. Once fixed in position, the graft cooperates with the surrounding tissues and replaces the damaged ACL.
It will be appreciated that there is a complex interdependency between the ACL and the other knee ligaments, bones and soft tissues. Consequently, the precise positioning of the graft ACL relative to the surrounding bones is critical to successful reconstruction of the knee joint. In particular, the positioning and formation of the bone tunnels must be precisely controlled by the surgeon.
In U.S. Pat. No. 4,672,957 to Hourahane; U.S. Pat. No. 4,722,331 to Fox; U.S. Pat. No. 4,739,751 to Sapega et al.; U.S. Pat. No. 4,781,182 to Purnell et al.; U.S. Pat. No. 4,920,958 to Walt et al.; U.S. Pat. No. 5,112,337 to Paulos et al.; U.S. Pat. No. 5,154,720 to Trott et al.; and U.S. Pat. No. 5,163,940 to Bourque, there are disclosed a variety of drill guide means for forming a positioned tunnel in the bones of a knee joint, or the like. The foregoing patents further disclose several different methods for using such drill guides.
Drill guide devices, such as those taught in the above-referenced patents, generally comprise a housing having an axial opening, a probe connected to the housing and having a tip that is adapted to be disposed within the interior of the knee at the distal point where one end of the tunnel is to exit the target bone, and a guidewire sleeve for directing a guidewire into position on the anterior surface of one of the bones of the knee joint. The housing is connected to the probe by an adjustable rack that is generally of a circular arc configuration. The housing is arranged so that its axial opening is more or less aligned to intersect with the aforementioned probe tip, and the guidewire sleeve is generally slidable or variable in position within the housing's axial opening. The relative angular position of the probe and the guidewire sleeve contained within the housing is slidably adjustable on the rack. All of the aforementioned parts are held in relation to one another by releasable locking means known in the art.
In ACL reconstruction, the known drill guide devices are used by first placing the probe tip at or near a predetermined location on the tibial plateau. Next, the guidewire sleeve is both angularly and longitudinally adjusted relative to the probe tip so that the distal end of the guidewire sleeve is directed toward the appropriate position on the anterior surface of the tibia. Once in place, the probe tip and guidewire sleeve are locked in position relative to each other by the aforementioned known locking means. Preferably, the probe tip and guidewire sleeve are locked into position while compressively engaging the tibia from two opposing directions, whereby the drill guide will be secured in proper position relative to the tibia.
Once the guidewire sleeve is adjusted and locked in position, a guidewire is slid through the guidewire sleeve and advanced (e.g., by drilling or tapping) through the tibia. The guidewire defines the tibial tunnel drilling axis. When the guidewire is seated in position in the tibia, the guidewire sleeve is unlocked and removed, longitudinally, back along the guidewire. The housing, probe and rack are then removed, leaving the guidewire embedded in the tibia. A cannulated drill bit is then slid over the guidewire to drill the tibial tunnel according to methods known to those skilled in the art. Thus, the tibial tunnel is drilled after the drill guide device has been removed from the patient. In other words, the drill guide device serves only to emplace the guidewire, and it is removed before the cannulated drill bit is introduced onto the guidewire.
It should be appreciated that, with the foregoing arrangement, while the position of the guidewire itself in the tibia is well set, in some situations the cannulated drill bit may be oriented in a manner in which the axis thereof fails to coincide with the axis of the guidewire in the tibia, leading to damage in the guidewire and the production of a tunnel not entirely consistent with the placement of the guidewire.
Further, coring drill bits are sometimes used to obtain a core of bone while producing the tibial tunnel, for purposes of later using that core to anchor a graft or to fill previously created bone defects from graft harvesting. The coring drill is generally a tubular structure with cutting teeth at the distal end. The internal diameter of the coring drill is much greater than the external diameter of the guidewire. As such, the current coring drill bits generally fail to provide adequate centering about the guidewire at the distal end of the coring drill. On occasion the guidewire may actually bend to the point where the coring drill bit's distal end cutting teeth cut across the guidewire itself.
Also, when coring drill bits are used to obtain a bone core while producing the tibial tunnel, on occasion the core is lost or damaged by virtue of slipping from the bit and falling or, conversely, by the inability to coax the core out of the bit.
Accordingly, there exists a need for a drill guide assembly having means for connecting the distal end of the guidewire to the tip of the probe so as to render the drill guide assembly more stable after the guidewire has been placed in the bone and the guidewire sleeve removed.
There also exists a need for an improved drill guide assembly in which the assembly may be left in place about the tibia while the bone tunnel is formed in the tibia.
There further exists a need for a drill guide assembly in which the coring drill can be properly centered about the guidewire during drilling.
There also exists a need for a drill guide assembly in which a bone core captured in a coring drill bit may be safely retained in the bit until needed, and then may be thereafter easily removed.